LONDON -- The FTSE 100 (INDEX: ^FTSE) isn't doing much today. The index of top U.K. shares is up a meager 12 points, or 0.19%, as of 9:25 a.m. EDT. Recent economic news has failed to clarify the medium-term outlook, and many are waiting for the next moves from central banks -- although the formation of a government in Italy has at least eliminated one bit of uncertainty.

News for companies is not all good today, either, with profit warnings taking some of the shine off recent upbeat earnings reports. Here are three companies slipping today.

Balfour Beatty
Balfour Beatty shares have slumped 10.2% this morning after the construction company issued its second profit warning in six months. The firm's U.K. construction business is now "expected to deliver significantly lower profits from operations for 2013 than management's expectations at the time of the full-year results announcement in March," as tough market conditions over the second half of 2012 are continuing.

Profit from U.K. construction is likely to be reduced by about 50 million pounds, or 20%, from previous expectations, with an additional profit deterioration of 10 million pounds expected from the firm's German rail operations.

Another profit warning, this time from Greggs, sent shares in the high-street baker tumbling by 7.5%. Blaming adverse weather in January and March, Greggs revealed a 4.4% fall in like-for-like sales, although there are signs that the drop has been leveling off in recent weeks.

The company said, "We do not expect a significant improvement in the difficult underlying market conditions in the short term," and that profit should be "slightly below the lower end of the range of market expectations." But even taking that into account, the year-end prospective P/E looks likely to be around 11.5, and if it's maintained, there's a dividend yield of around 4.5% forecast.

Nanoco (LSE:NANO)
Quantum dot developer Nanoco has seen its shares falter a little, down 2% after the firm announced that nonexecutive chairman Peter Rowley is to step down from the position after serving seven years in the chair. Rowley will become a nonexecutive director, with current nonexecutive director Anthony Clinch taking over the chairman role.

Nanoco's shareholders have been rewarded nicely over the past 12 months, with the price more than doubling -- though earlier in 2013 the shares were changing hands for as much as 199 pence.

Finally, reliable dividends can more than compensate for the day-to-day ups and downs of share prices. So how about a company that's offering a 5.7% yield and could be set for some nice share-price appreciation, too? It's the subject of our brand-new report "The Motley Fool's Top Income Share For 2013," which you can get completely free of charge -- but it will only be available for a limited period, so click here to get your copy today.

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